Attempts have been made in the past to detect improper operation of a needle or catheter as evidenced by U.S. Pat. No. 3,853,118. Devices of this sort are limited in their capability and, in particular, point out some of the medical problems associated with intravenous infusions into the human body.
Customarily, IV infusions are achieved by inserting a needle or catheter of the proper gage cannula typically just under the skin and into a suscutaneous vein. Two or three problems typically occur. At the time of insertion of the cannula, the medical personnel may believe that it was inserted without lateral movement into a presumably straight vein when in fact the point was laterally misaligned or otherwise contacted against the vein wall thereby forming tears or scratches on interior vein walls which are undesirable. The cannula may be too large for the vein. Further, the venipuncture site may not seal around the cannula. On insertion through the layers of subsurface skin (dermis and epidermis) including the wall of a vein, leakage (extravasation) may occur back along the cannula. Even if the cannula is prefectly placed in the vein with no problems, subsequent patient movement can inadvertently force the cannula through a vein to infuse the IV fluid into body tissue (otherwise known as infiltration). This leakage between layers of the skin sometimes is very harmful because the IV solution is delivered to the wrong part of the body of the patient typically causing phlebitis or thrombophlebitis. A further problem is enlargement of the small openings formed by the cannula and resultant chemical or hydraulic action of the IV solution. That is to say, the cannula is correctly inserted but after it has been in place for a period of time, extravasation along the pinhole sized openings formed in the path of the cannula may occur and thereby cause swelling to be formed in the near vicinity.
Most of the problems which arise with difficulty in IV infusions are evidenced with a slight early swelling in the immediate area. The swelling is very slight and difficult to observe in the beginning. However, it is at this juncture that remedial steps are most effective. Given the situation where a person has been hospitalized for a substantial period of time and has been given many IV injections, the nursing personnel typically have great difficulty in maintaining and keeping open veins for repetitive infusions. If a problem arises with the IV infusion at the site of needle insertion, it takes several days, even weeks in an older person, for the localized bruising and trama to heal. This forces the nursing personnel to seek another site for IV infusions, and upon an extended hospitalization, such sites are not readily available.
Other sources of edema exist. Causes are numerous and are varied as medical problems but typical causes include phlegmasia, pulmanary edema, venostasis, vascular occlusions, trauma, surgical incisions, contusions, sprains, fractures, and so on. These are noted by competent nursing personnel who detect color changes or localized swelling, normally achieved by a combination of visual inspection and localized palpation.
In summary, the exemplary problems point out why proper IV infusions are desirable; proper IV infusions assure that the patient receives the desired infusion in timely fashion, side effects are eliminated, and the personnel does not lose infusion sites, an especially critical problem in long term hospitalizations.
With the foregoing edema problems in view, the present apparatus is a device which detects swelling in the near vicinity of the site of an IV infusion or some other source of edema. It is sensitive and therefore able to provide a prompt and early indication of swelling so that remedial steps can be taken quickly to avoid aggrevated problems. The signal is provided sufficiently promptly to enable removal of the needle or aleviation of the source of edema so that the problem is not aggrevated by continued swelling and accumulation of IV fluids at an unintended location. If the infusible is not delivered to the intended location, the medication may be lost and the planned program of treatment will be delayed and recovery will be delayed. More importantly, this apparatus is able to be attached at any point of the body where a needle is inserted into the human body. It can be attached close to an incision or fracture beneath a bandage or cast. Typically, needles are inserted in the veins of the arms or legs but the apparatus is not limited to those locations. It is able to be attached without the use of a tourniquet or pressure cuff extending around the limb or trunk of the body. Moreover, it can be left unattached and yet forms a signal which sounds through an appropriate alarm device an alarm to nursing personnel. As a result of the use of the present device, localized trauma and edema in the vicinity of the site of an IV infusion or other edema is thereby avoided and the problems associated with a localized injury are thereby either reduced or avoided.